Rhinichthys osculus - (Girard, 1856)
Speckled Dace
Taxonomic Status: Accepted
Related ITIS Name(s): Rhinichthys osculus (Girard, 1856) (TSN 163387)
Unique Identifier: ELEMENT_GLOBAL.2.100335
Element Code: AFCJB37050
Informal Taxonomy: Animals, Vertebrates - Fishes - Bony Fishes - Minnows and Carps
Kingdom Phylum Class Order Family Genus
Animalia Craniata Actinopterygii Cypriniformes Cyprinidae Rhinichthys
Genus Size: C - Small genus (6-20 species)
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Concept Reference
Concept Reference: Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 pp.
Concept Reference Code: B91ROB01NAUS
Name Used in Concept Reference: Rhinichthys osculus
Taxonomic Comments: According to Hoekzema and Sidlauskas (2014), three highly divergent clades warrant species-level status: Malheur stream dace, Stinking Lake Spring dace, and dace from the other four basins combined (Goose Lake, Silver Lake, Lake Abert, and Warner, inclusive of Foskett Spring). In agreement with Ardren et al. (2010), Hoekzema and Sidlauskas (2014) determined that Foskett Spring speckled dace is not monophyletic and does not warrant species or subspecies status. However, they recommend it be recognized as an Evolutionarily Significant Unit within the broader concept of Rhinichthys osculus.

The speckled dace is one of the most morphologically (and ecologically) variable fishes in western North America (Miller and Miller 1948, Minckley 1973). This variability is due to geologic events that have resulted in numerous isolated populations. This variability also reflects inadequate information on population interrelationships. Minckley (1985) referred to the "speckled dace" complex, which reflects the view of many taxonomists that several species are now referred to as Rhinichthys osculus. Further taxonomic and systematic work is needed.

MtDNA data suggest the existence of two prominent clades, corresponding with populations in the Colorado River and Snake River (Oakey et al. 2004, which see for further discussion of the phylogeography of the complex).

Peden and Hughes (1988) and Page and Burr (1991) regarded subspecies umatilla as a distinct species, based on sympatry between umatilla and another osculus subspecies in certain parts of the Columbia River drainage in Canada. However, Robins et al. (1991) noted R. osculus is notoriously variable and pointed out that the type locality of umatilla is much farther south in the Columbia system than the Canadian localities; hence the 1991 AFS checklist did not recognize umatilla as a valid species.

Hybridizes with Rhinichthys cataractae.
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 25Sep1996
Global Status Last Changed: 25Sep1996
Rounded Global Status: G5 - Secure
Reasons: Large range in most of the western states; very abundant in many areas; secure overall.
Nation: United States
National Status: N5 (05Dec1996)
Nation: Canada
National Status: N2 (02Nov2017)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Arizona (S3S4), California (SNR), Colorado (S5), Idaho (S5), Navajo Nation (S5), Nevada (S5), New Mexico (S3), Oregon (S4), Utah (S4), Washington (S5), Wyoming (S4)
Canada British Columbia (S2)

Other Statuses

Implied Status under the U.S. Endangered Species Act (USESA): PS
Comments on USESA: Foskett speckled dace, R. osculus ssp. 3, (from Oregon) is listed as Threatened but proposed delisted (USFWS 2018). Subspecies thermalis, nevadensis (see Williams and Sada 1985), oligoporus, and lethoporus are listed as Endangered (USFWS 1987, USFWS 1990). Subspecies reliquus is extinct.

Ten subspecies of speckled dace were listed by Deacon et al. (1979) and Williams et al. (1989) as endangered, threatened or of special concern: Rhinichthys osculus lethoporus, Independence Valley speckled dace, Nevada; R. o. nevadensis, Ash Meadows speckled dace, Nevada; R. o. oligoporus, Clover Valley speckled dace, Nevada; R. o. thermalis, Kendall Warm Springs speckled dace, Wyoming; R. o. moapae, Moapa River, Nevada; R. o. ssp., Foskett speckled dace, Oregon; R. o. ssp., Amaragosa River speckled dace, Nevada; R. o. ssp., Owens speckled dace, California; R. o. ssp., Preston speckled dace, Nevada; and R. o. ssp., Santa Ana speckled dace, California.

Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: E (05Mar2009)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Endangered (27Nov2016)
Comments on COSEWIC: The species is restricted to the Kettle River mainstem and two main tributaries in southcentral British Columbia where it appears to be limited by the availability of suitable habitat. As this population is isolated above Cascade Falls, it can not be rescued from downstream United States populations. The Kettle River is a flow-sensitive system that appears to be experiencing increasing frequency of drought conditions. The species is threatened by these reduced water flows and projected increasing water demands.

Designated Special Concern in April 1980. Status re-examined and designated Endangered in November 2002, April 2006, and in November 2016.

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent Comments: The most ubiquitous fish in the western U.S. (Page and Burr 1991), ranging from the Columbia River drainage (north to southern British Columbia) to the southern Gila River drainage of Arizona and Sonora, Mexico (Peden and Hughes 1981, Minckley et al. 1986, Varela-Romero 1990, Wallace 1980); ecological range extends from small springs of Death Valley to high mountain brooks (Minckley 1985), including waters of the Columbia River basin, Klamath River basin, Oregon lakes, Lahontan basin, Bonneville basin, North-Central basins, Death Valley system, Sacramento River basin, Colorado River basin, and South California Coastal Region (Minckley et al. 1986). [Subspecies osculus was described from Babocomari Creek, Arizona (Girard 1856), but is extirpated there. R. o. osculus now occurs only in about half a dozen locations, including Aravaipa Creek, Cave Creek (Chiricahua Mountains), Redfield Canyon, and Sonoita Creek, Arizona (Minckley 1981, Minckley 1991).]

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Most ubiquitous freshwater fish of the western states.

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: Abundant in many areas.

Overall Threat Impact Comments: Not threatened overall, but small local populations are vulnerable to habitat alteration and exotic species. Reasons for decline include dewatering of springs, headwaters, and middle portions of major streams, water impoundment, channelization, diversion, regulation of discharges, and interactions with non-native species (Minckley 1985, Moyle et al. 1989). Subspecies reliquus, of Grass Valley, eastern Lander County, Nevada, is extinct due to introduction of trout and possibly use of water for agriculture (Miller et al. 1989). See Taylor et al. (1989) for information on negative impact of cattle on desert spring populations (chemical alteration of water). Miller (1961) hypothesized that extirpation in the San Pedro River, Arizona, was due to elevated water temperatures caused by entrenchment, diminished vegetation, and decreasing flows. Cross (1975) hypothesized that the decline in the Virgin River was due to introduction of non-native fishes, decreases in discharge and increased water pollution.

Short-term Trend Comments: Miller (1961) and Minckley (1973) reported that speckled dace disappeared from larger rivers at elevations below approximately 1500 m in the Gila drainage of Arizona between 1850 to 1950. LaBounty and Minckley (1972) reported that numbers of speckled dace have declined in the Gila River system in general. Reductions in speckled dace are especially notable in the southern Gila River drainage (Hendrickson 1991, Minckley 1969, Minckley 1991). Miller (1961) documented that speckled dace were present in the San Pedro river, Arizona, in 1850 and 1904, but had disappeared by 1939. Cross (1975) found that at some time after 1942 speckled dace had been eliminated in the Virgin River below Littlefield, Arizona.

Other NatureServe Conservation Status Information

Global Range: The most ubiquitous fish in the western U.S. (Page and Burr 1991), ranging from the Columbia River drainage (north to southern British Columbia) to the southern Gila River drainage of Arizona and Sonora, Mexico (Peden and Hughes 1981, Minckley et al. 1986, Varela-Romero 1990, Wallace 1980); ecological range extends from small springs of Death Valley to high mountain brooks (Minckley 1985), including waters of the Columbia River basin, Klamath River basin, Oregon lakes, Lahontan basin, Bonneville basin, North-Central basins, Death Valley system, Sacramento River basin, Colorado River basin, and South California Coastal Region (Minckley et al. 1986). [Subspecies osculus was described from Babocomari Creek, Arizona (Girard 1856), but is extirpated there. R. o. osculus now occurs only in about half a dozen locations, including Aravaipa Creek, Cave Creek (Chiricahua Mountains), Redfield Canyon, and Sonoita Creek, Arizona (Minckley 1981, Minckley 1991).]

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AZ, CA, CO, ID, NM, NN, NV, OR, UT, WA, WY
Canada BC

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Apache (04001), Cochise (04003), Coconino (04005), Gila (04007), Graham (04009), Greenlee (04011), Maricopa (04013), Mohave (04015), Navajo (04017), Pinal (04021), Santa Cruz (04023), Yavapai (04025)
CA Inyo (06027), Los Angeles (06037), Mono (06051), Orange (06059), Riverside (06065), San Bernardino (06071)
CO Montezuma (08083)
NM Catron (35003), Grant (35017), Mckinley (35031), Rio Arriba (35039)*, San Juan (35045), Sierra (35051)*
NV Clark (32003), Elko (32007), Eureka (32011)*, Lander (32015)*, Lincoln (32017), Nye (32023), White Pine (32033)
OR Lake (41037)*
UT Box Elder (49003), Cache (49005), Carbon (49007), Davis (49011), Duchesne (49013), Emery (49015), Garfield (49017), Grand (49019), Iron (49021), Juab (49023), Kane (49025), Millard (49027), Morgan (49029), Piute (49031), Rich (49033), Salt Lake (49035), San Juan (49037), Sanpete (49039), Sevier (49041), Summit (49043), Tooele (49045), Uintah (49047), Utah (49049), Wasatch (49051), Washington (49053), Wayne (49055), Weber (49057)
WY Sublette (56035)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
13 Plains of San Agustin (13020208), Mimbres (13030202)+
14 Colorado headwaters (14010001), Colorado headwaters-Plateau (14010005), Parachute-Roan (14010006), Upper Gunnison (14020002), North Fork Gunnison (14020004), Lower Gunnison (14020005), Uncompahange (14020006), Westwater Canyon (14030001)+, Upper Dolores (14030002), San Miguel (14030003), Lower Dolores (14030004), Upper Colorado-Kane Springs (14030005)+, Upper Green (14040101)+, New Fork (14040102), Upper Green-Slate (14040103), Big Sandy (14040104), Bitter (14040105), Upper Green-Flaming Gorge Reservoir (14040106), Blacks Fork (14040107), Muddy (14040108), Vermilion (14040109), Upper Yampa (14050001), Lower Yampa (14050002), Little Snake (14050003), Muddy (14050004), Upper White (14050005), Piceance-Yellow (14050006), Lower White (14050007)+, Lower Green-Diamond (14060001)+, Ashley-Brush (14060002)+, Duchesne (14060003)+, Strawberry (14060004)+, Lower Green-Desolation Canyon (14060005)+, Willow (14060006)+, Price (14060007)+, Lower Green (14060008)+, San Rafael (14060009)+, Upper Lake Powell (14070001), Muddy (14070002)+, Fremont (14070003)+, Dirty Devil (14070004)+, Escalante (14070005)+, Lower Lake Powell (14070006), Paria (14070007)+, Upper San Juan (14080101)+, Piedra (14080102), Blanco Canyon (14080103)+, Animas (14080104)+, Middle San Juan (14080105)+, Mancos (14080107), Lower San Juan-Four Corners (14080201)+, Mcelmo (14080202)+, Montezuma (14080203), Chinle (14080204)+, Lower San Juan (14080205)+
15 Lower Colorado-Marble Canyon (15010001)+, Grand Canyon (15010002)+, Kanab (15010003)+, Lake Mead (15010005)+, Grand Wash (15010006), Upper Virgin (15010008)+, Fort Pierce Wash (15010009)+, Lower Virgin (15010010)+, White (15010011)+, Muddy (15010012)+, Meadow Valley Wash (15010013)+, Little Colorado headwaters (15020001)+, Upper Little Colorado (15020002), Carrizo Wash (15020003)+*, Zuni (15020004)+, Silver (15020005)+, Upper Puerco (15020006)+, Middle Little Colorado (15020008)+, Chevelon Canyon (15020010)+, Canyon Diablo (15020015), Lower Little Colorado (15020016)+, Havasu-Mohave Lakes (15030101), Big Sandy (15030201)+, Burro (15030202)+, Santa Maria (15030203), Upper Gila (15040001)+, Upper Gila-Mangas (15040002)+, San Francisco (15040004)+, Upper Gila-San Carlos Reservoir (15040005)+, San Simon (15040006)+, San Carlos (15040007), Upper San Pedro (15050202), Lower San Pedro (15050203)+, Upper Santa Cruz (15050301)+, Rillito (15050302), Black (15060101)+, White (15060102), Upper Salt (15060103)+, Carrizo (15060104), Tonto (15060105)+, Lower Salt (15060106), Big Chino-Williamson Valley (15060201)+, Upper Verde (15060202)+, Lower Verde (15060203)+, Agua Fria (15070102)+
16 Upper Bear (16010101)+, Central Bear (16010102), Bear Lake (16010201), Middle Bear (16010202)+, Little Bear-Logan (16010203)+, Lower Bear-Malad (16010204)+, Upper Weber (16020101)+, Lower Weber (16020102)+, Utah Lake (16020201)+, Spanish Fork (16020202)+, Provo (16020203)+, Jordan (16020204)+, Hamlin-Snake Valleys (16020301)+, Pine Valley (16020302), Tule Valley (16020303), Rush-Tooele Valleys (16020304)+, Southern Great Salt Lake Desert (16020306)+, Northern Great Salt Lake Desert (16020308)+, Upper Sevier (16030001)+, East Fork Sevier (16030002)+, Middle Sevier (16030003)+, San Pitch (16030004)+, Lower Sevier (16030005)+, Escalante Desert (16030006)+, Beaver Bottoms-Upper Beaver (16030007), Lower Beaver (16030008), Sevier Lake (16030009), Upper Quinn (16040201), Smoke Creek Desert (16040203), Massacre Lake (16040204), Lake Tahoe (16050101), Truckee (16050102), Upper Carson (16050201), East Walker (16050301), West Walker (16050302), Northern Big Smoky Valley (16060004)+, Diamond-Monitor Valleys (16060005)+, Long-Ruby Valleys (16060007)+
17 Pend Oreille Lake (17010214), Pend Oreille (17010216), Upper Coeur D'alene (17010301), St. Joe (17010304), Upper Spokane (17010305), Hangman (17010306), Lower Spokane (17010307), Little Spokane (17010308), Franklin D. Roosevelt Lake (17020001), Kettle (17020002), Colville (17020003), Sanpoil (17020004), Chief Joseph (17020005), Okanogan (17020006), Methow (17020008), Upper Columbia-Entiat (17020010), Wenatchee (17020011), Moses Coulee (17020012), Upper Crab (17020013), Banks Lake (17020014), Lower Crab (17020015), Upper Columbia-Priest Rapids (17020016), Upper Yakima (17030001), Naches (17030002), Lower Yakima, Washington (17030003), Snake headwaters (17040101), Gros Ventre (17040102), Greys-Hobock (17040103), Palisades (17040104), Salt (17040105), Idaho Falls (17040201), Upper Henrys (17040202), Lower Henrys (17040203), Willow (17040205), American Falls (17040206), Blackfoot (17040207), Portneuf (17040208), Lake Walcott (17040209), Raft (17040210), Goose (17040211), Upper Snake-Rock (17040212), Beaver-Camas (17040214), Big Wood (17040219), Camas (17040220), Little Wood (17040221), C. J. Idaho (17050101), Bruneau (17050102), Middle Snake-Succor (17050103), East Little Owyhee. Nevada, (17050106), Middle Owyhee (17050107), Jordan (17050108), Crooked-Rattlesnake (17050109), Lower Owyhee (17050110), North and Middle Forks Boise (17050111), Boise-Mores (17050112), Lower Boise (17050114), Middle Snake-Payette (17050115), Upper Malheur (17050116), Lower Malheur (17050117), Bully (17050118), Willow (17050119), South Fork Payette (17050120), North Fork Payette (17050123), Weiser (17050124), Brownlee Reservoir (17050201), Burnt (17050202), Powder (17050203), Hells Canyon (17060101), Imnaha (17060102), Lower Snake-Asotin (17060103), Upper Grande Ronde (17060104), Wallowa (17060105), Lower Grande Ronde (17060106), Lower Snake-Tucannon (17060107), Palouse (17060108), Rock (17060109), Lower Snake (17060110), Upper Salmon (17060201), Middle Salmon-Panther (17060203), South Fork Salmon (17060208), Little Salmon (17060210), Upper Selway (17060301), Lower Selway (17060302), Lochsa (17060303), Middle Fork Clearwater (17060304), South Fork Clearwater (17060305), Clearwater (17060306), Upper North Fork Clearwater (17060307), Lower North Fork Clearwater (17060308), Middle Columbia-Lake Wallula (17070101), Walla Walla (17070102), Umatilla (17070103), Willow (17070104), Middle Columbia-Hood (17070105), Klickitat (17070106), Upper John Day (17070201), North Fork John Day (17070202), Middle Fork John Day (17070203), Lower John Day (17070204), Upper Deschutes (17070301), Beaver-South Fork (17070303), Upper Crooked (17070304), Lower Crooked (17070305), Lower Deschutes (17070306), Trout (17070307), Lower Columbia-Sandy (17080001), Lewis (17080002), Lower Columbia-Clatskanie (17080003), Upper Cowlitz (17080004), Lower Cowlitz (17080005), Lower Columbia (17080006), Middle Fork Willamette (17090001), Coast Fork Willamette (17090002), Upper Willamette (17090003), Mckenzie (17090004), North Santiam (17090005), South Santiam (17090006), Middle Willamette (17090007), Yamhill (17090008), Molalla-Pudding (17090009), Tualatin (17090010), Clackamas (17090011), Lower Willamette (17090012), Hoh-Quillayute (17100101), Queets-Quinault (17100102), Upper Chehalis (17100103), Lower Chehalis (17100104), Grays Harbor (17100105), Willapa Bay (17100106), Siletz-Yaquina (17100204), Alsea (17100205), Siuslaw (17100206), Siltcoos (17100207), North Umpqua (17100301), South Umpqua (17100302), Umpqua (17100303), Coos (17100304), Coquille (17100305), Sixes (17100306), Upper Rogue (17100307), Middle Rogue (17100308), Applegate (17100309), Lower Rogue (17100310), Illinois (17100311), Snoqualmie (17110010), Lake Washington (17110012), Duwamish (17110013), Puyallup (17110014), Nisqually (17110015), Deschutes (17110016), Skokomish (17110017), Puget Sound (17110019), Harney-Malheur Lakes (17120001), Silvies (17120002), Donner Und Blitzen (17120003), Silver (17120004), Summer Lake (17120005), Lake Abert (17120006), Warner Lakes (17120007)+, Guano (17120008)
18 Smith (18010101), Williamson (18010201), Sprague (18010202), Upper Klamath Lake (18010203), Lost (18010204), Butte (18010205), Upper Klamath (18010206), Shasta (18010207), Scott (18010208), Lower Klamath (18010209), Salmon (18010210), Trinity (18010211), South Fork Trinity (18010212), Goose Lake (18020001), Upper Pit (18020002), Lower Pit (18020003), Mccloud (18020004), Sacramento headwaters (18020005), Sacramento-Lower Cow-Lower Clear (18020101), Lower Cottonwood (18020102), Sacramento-Lower Thomes (18020103), Sacramento-Stone Corral (18020104), Lower Butte (18020105), Lower Feather (18020106), Lower Yuba (18020107), Lower Bear (18020108), Lower Sacramento (18020109), Lower Cache (18020110), Lower American (18020111), Sacramento-Upper Clear (18020112), Cottonwood headwaters (18020113), Upper Elder-Upper Thomes (18020114), Upper Stony (18020115), Upper Cache (18020116), Upper Putah (18020117), Upper Cow-Battle (18020118), Mill-Big Chico (18020119), Upper Butte (18020120), North Fork Feather (18020121), East Branch North Fork Feather (18020122), Middle Fork Feather (18020123), Honcut headwaters (18020124), Upper Yuba (18020125), Upper Bear (18020126), Upper Coon-Upper Auburn (18020127), North Fork American (18020128), South Fork American (18020129), Upper Los Gatos-Avenal (18030011), San Joaquin Delta (18040003), Lower Calaveras-Mormon Slough (18040004), Lower Cosumnes-Lower Mokelumne (18040005), Upper Stanislaus (18040010), Upper Calaveras (18040011), Upper Mokelumne (18040012), Upper Cosumnes (18040013), Coyote (18050003), San Francisco Bay (18050004), Pajaro (18060002), Salinas (18060005), Cuyama (18060007), Los Angeles (18070105)+, San Gabriel (18070106)+, Santa Ana (18070203)+, Surprise Valley (18080001), Madeline Plains (18080002), Honey-Eagle Lakes (18080003), Crowley Lake (18090102)+, Owens Lake (18090103)+, Upper Amargosa (18090202)+, Death Valley-Lower Amargosa (18090203)+, Indian Wells-Searles Valleys (18090205)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
Basic Description: A small fish (dace).
General Description: The following description is from Minckley (1973) and Sublette et al. (1990). The speckled dace is a chunky, rounded minnow. Adults reach lengths of 45-80 mm standard length (SL = length from tip of snout to end of hypural plate) (Wallace 1980). Usually there are 8 dorsal rays (6-9), 13-14 pectoral rays, 8 pelvic rays, and 7 anal rays. There are 60-90 scales along the lateral line. The mouth is subterminal, usually with no frenum. Pharyngeal arches contain teeth in two rows, usually 1,4-4,1 or 2,4-4,2. A single, small barbel is located at the edge of each jaw. Coloration is variable depending on geographic location, but often dark and blotchy dorsally, lighter ventrally. A lateral band extends from the dorsal fin onto the caudal peduncle. Breeding males have an intense red color at the base of paired fins, near the anal fin base, on the lower caudal lobe, near the upper part of the gill cleft, and on the mouth. Breeding tubercles are present on pectoral rays of males. Larval speckled dace from the upper and lower Colorado River basin were described by Snyder (1981) and Winn and Miller (1954), respectively.
Diagnostic Characteristics: In Arizona and New Mexico, the speckled dace is morphologically most similar to TIAROGA COBITIS, the loach minnow, with which it often occurs syntopically. The speckled dace differs in having a single barbel at each side of the upper lip and the mouth is relatively larger and less oblique than in loach minnow. The loach minnow possesses more dorsally oriented eyes than does the speckled dace. Other meristic counts are the same or overlap in the two species. Both species have a blotchy appearance, but the speckled dace lacks off-white spots before and after the dorsal fin and on the caudal peduncle.

Smaller specimens of speckled dace might be confused with AGOSIA CHRYSOGASTER, the longfin dace, which is syntopic with the speckled dace in parts of its range. Longfin dace has a long coiled intestine and a black peritoneum; speckled dace has an S-shaped intestine and light peritoneum.

Reproduction Comments: Cross (1975) collected ripe females in late June and mid-July 1973 from the Virgin River drainage in Utah. In Aravaipa Creek, Arizona, speckled dace were collected in breeding coloration or with tubercles from December to August, with mature gonads from November to March, or seen engaged in spawning activities from January to April. Larvae were collected from January to April.

John (1963) studied reproduction in Cave Creek, Chiricahua Mountains, Arizona. Females matured at two years of age. Peaks in reproductive activity were in early spring and late summer. John believed spawning efforts were triggered by flash floods. Males defended territories, and activities of the male often resulted in circular, clean gravel areas that John (1963) called nests. A female entered a defended area and partially buried or wedged herself under the edge of a stone. Males took positions next to the buried female and the pair or group vibrated for a few seconds, after which the female departed. A female entered a nest several times, depositing a portion of her ripe eggs during each spawning event. John (1963) gave data for the total number of eggs laid in an aquarium by each of eight females. From these data, Vives calculated that the number of eggs laid was related to standard length by the equation: number of eggs laid = -264.41 + 10.45 SL (mm) (R- squared = 0.89, p < 0.001). Females ranged from 45 to 75 mm SL and numbers of eggs laid ranged from 174 to 514. Eggs hatched in 6 days at 18 to 19 C under laboratory conditions.

Maximum age of speckled dace in streams of the Chiricahua Mountains is 3 years (John 1964). Moyle et al. (1989) stated that some may live up to 5-6 years.

Females from the Kettle River, British Columbia, Canada, did not mature until the end of their second year (Peden and Hughes 1981).

Ecology Comments: Associated with several different faunas depending on location. In the Gila River drainage, native associates include the spikedace (MEDA FULGIDA), roundtail chub (GILA ROBUSTA), loach minnow (TIAROGA COBITIS), longfin dace (AGOSIA CHRYSOGASTER), Sonora sucker (CATOSTOMUS INSIGNIS), desert sucker (CATOSTOMUS CLARKI), and Gila trout (ONCORYNCHUS GILAE). Historical associates included the woundfin (PLAGOPTERUS ARGENTISSIMUS), bonytail (GILA ELEGANS), squawfish (PTYCHOCHEILUS LUCIUS), flannelmouth sucker (CATOSTOMUS LATIPINNIS), and razorback sucker (XYRAUCHEN TEXANUS), all now extirpated from the Gila River basin.

Populations show large fluctuations in size (Minckley 1969, Deacon and Bradley 1972). LaBounty and Minckley (1972) noted that increasing populations of longfin dace may result in decreasing populations of speckled dace in areas of overlap at intermediate elevations. There is not enough data to understand the nature of this relationship (i.e., whether or not it is cause-effect).

Predators include introduced trouts (ONCORHYNCHUS AND SALMO spp.) in the Colorado River mainstream, flathead catfish (PYLODICTUS OLIVARIS) in the Salt River basin, and also introduced basses (MICROPTERUS spp.) and green sunfish (CHAENOBRYTTUS CYANELLUS) (Minckley 1985). THAMNOPHIS CYRTOPSIS (black-necked garter snake) is known to feed on speckled dace (John 1964).

Mpoame and Rinne (1983) recorded the protozoan ICHTHYOPHTHIRIUS MULTIFILIIS, trematode ORNITHODIPLOSTOMUM PTYCHOCHEILUS, and the cestode LIGULA INTESTINALIS as parasites of speckled dace in Aravaipa and Hurricane creeks, Arizona.

Generally occurs in small, loose groups.

Habitat Type: Freshwater
Non-Migrant: Y
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Lake populations may migrate short distances up inlet streams to spawn.
Riverine Habitat(s): CREEK, MEDIUM RIVER, Moderate gradient, Pool, Riffle, SPRING/SPRING BROOK
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Benthic
Habitat Comments: Occurs in many kinds of habitats: riffles, runs, and pools of cool flowing headwaters, creeks, and small to medium rivers with mostly rocky substrates; large and small lakes (rarely); warm, permanent and intermittent streams; and outflows of desert springs (Moyle 1976); usually found in shallow water (averaging about 0.5 m deep or less); in streams, often congregates below riffles and eddies (Minckley 1973). Young tend to occupy edges of streams in slower, shallow water (Cross 1975). Larger adults generally are in relatively quiet water where cover (e.g., overhanging trees, deadfalls, boulders) is available (Minckley 1985).

Stream populations spawn in swift water over rocky substrates. Lake populations spawn in shallow waters with gravel substrate or on gravel edge of riffles in inlet streams (Moyle 1976). In Aravaipa Creek, Arizona, spawning occurred over rapids and riffles, at depths less than 25 cm, over substrates of gravel, cobble, or rubble (Minckley 1981).

Mueller (1984) described spawning behavior of speckled dace in the San Francisco River, New Mexico. Spawning occurred in a 1-m square section of stream recently scoured by human activity. Spawning clusters formed, each with more than 25 fish. Dace thrashed violently (presumable at spawning) and eggs were found at depths to 5 cm. Most eggs were unexposed, attached to undersides of rocks or in interstices between rocks. Territoriality or spawning pairs were not observed.

In the Virgin River (Utah, Arizona, Nevada), speckled dace were collected from 500 m to 1800 m elevation (Cross 1975). Sixty percent were collected in runs, 30 percent in pools, and 10 percent in riffles. Two-thirds of the collections were associated with gravel, rubble, or cobble substrates and one-third with sand and mud. Seventy percent were collected near some type of cover, usually overhanging trees, deadfalls, and boulders. Speckled dace were collected at current speeds averaging 0.43 m/sec (SD = 0.25 m/sec, range 0 to 1 m/sec) and at depths averaging 48 cm (SD = 43 cm).

Speckled dace from the Virgin River (Utah, Arizona, and Nevada) preferred an average temperature of 15.8 C (range 9.5 to 16 C, depending on acclimation temperature) (Deacon et al. 1987). Critical thermal maxima were 30.5, 32.6, and 36.8 C for dace acclimated at 10, 15, and 25 C (Deacon et al. 1987). Rangewide, however, the speckled dace is found at much higher average temperatures, such as 29 C at Ash Meadows, Nevada, 28 C at Pahranagat Valley, Nevada (Deacon and Bradley 1972), and 29.4 C at Kendall Springs in Wyoming (Hubbs and Kuehne 1937).

Lowe et al. (1967) showed that speckled dace, collected from Sonoita Creek, Arizona, were intolerant to elevated temperatures and reduced oxygen levels. Speckled dace were least tolerant to reduced oxygen levels when compared to Agosia chrysogaster, Catostomus clarki, and Cyprinodon macularius (Lowe et al. 1967).

Adult Food Habits: Herbivore, Invertivore
Immature Food Habits: Herbivore, Invertivore
Food Comments: An omnivorous benthic feeder, at times feeding on drift in mid-water or rarely at the surface (Schreiber and Minckley 1981). The diet consists mostly of benthic insects, also includes other invertebrates, algae, and detritus (little or no plant material or detritus in some areas) (Sublette et al. 1990, Woodbury 1933, Greger and Deacon 1988). Young feed mainly on zooplankton.

Of 97 individuals collected in October from the Columbia River drainage, Canada, 28 percent had consumed only filamentous algae, 39 percent contained only insect remains, and the remaining 33 percent contained algae and insect remains (Peden and Hughes 1981).

Schreiber and Minckley (1981) examined food habits in Aravaipa Creek, Arizona, during January, April, July, and October, 1975, and January 1976. The diet included primarily riffle-dwelling insects, reflecting the association with riffle habitats. Ephemeropteran larvae made up greater than 70 percent of the diet, excepting one sampling period. Plecopteran, trichopteran, and dipteran larvae were used when available

Speckled dace from Little Creek, New Mexico, collected on 18-20 June 1986, consumed primarily dipteran larvae (81 percent by number), ephemeropteran larvae (7 percent), and trichopteran larvae (4 percent) (van Eimeren 1988). At the same location, speckled dace collected on 24-26 October 1986 consumed dipteran larvae (47 percent by number), ephemeropteran larvae (29 percent) and trichopteran larvae (23 percent). Additionally, van Eimeren found little diet overlap between Gila trout and speckled dace even though they shared the same habitats.

Greger and Deacon (1988) examined food habits of speckled dace on 9 February, 20 June, 28 September, and 12 December 1979, in the Virgin River, Utah, Arizona, and Nevada. Dace fed mostly on simuliid larvae in February and June and on chironomid larvae in September and December.

Phenology Comments: In Lake Tahoe, California, most active at night, inactive during the winter. In New Mexico, feeds primarily between 9:00 p.m. and 1:00 a.m. In streams may be active throughout the year (Moyle 1976). Carter et al. (1986) studied larval drift of upper Colorado River fishes in Colorado from mid-June to September. Speckled dace made up 16-18% of larvae captured. More larvae were captured near shore than midstream. Highest numbers of larvae were captured between 2000 and 0400 h, and lowest numbers between 1600 and 2000 h, suggesting a diurnal pattern of avoidance of daylight.
Length: 8 centimeters
Economic Attributes
Economic Comments: Used as a bait fish in some areas. May be important as a forage species.
Management Summary
Preserve Selection & Design Considerations: Although adaptable and exhibiting remarkable dispersal and recolonization capabilities, speckled dace require permanent, unpolluted water. Preserves should be free of introduced predators such as green sunfish (LEPOMIS CYANELLUS) and the black-basses (MICROPTERUS spp.).

For stream-inhabiting forms of speckled dace, large stream areas (scale kilometers) must be preserved, including rapids, riffles, and runs with rocky substrates. Riffles with gravel, cobble, and rubble substrates must be present for use as spawning areas. Fry and juveniles need adequate slow water nursery areas (e.g., pools and stream margins).

The importance in retaining a natural flow regime in southwestern streams has been emphasized by Meffe and Minckley (1987) and Minckley and Meffe (1987). Not only does flooding reduce populations of non-native fishes, periodic flooding may be used as a cue for breeding in speckled dace (John 1963).

Springs that contain speckled dace must retain sufficient water for the dace to complete its life history requirements. Additionally, sources of pollution must be eliminated and exotic fishes removed if they are adversely impacting the speckled dace population.

Management Requirements: For discussion of management concerns for populations in desert springs, see USFWS (1987).
Monitoring Requirements: See Gori (1995) for a monitoring plan for this and other native fishes at Patagonia-Sonoita Creek Preserve.
Biological Research Needs: Knowledge of speckled dace life history is surprisingly incomplete given their range and ubiquity. The following specific topics are among those that need to be addressed: (1) systematic relationships of populations currently classified as speckled dace, (2) dispersal abilities and impacts of barriers, (3) larval biology (e.g., habitat, diet, dispersal), (4) age and growth, (5) nature of interactions with introduced species, (6) effects of physical habitat modification and pollution on life cycle completion, (7) spawning activities at different geographic locations, (8) factors that trigger spawning, (9) fecundity, (10) frequency of spawning for males and females, and (11) natural fluctuations in population size.
Population/Occurrence Delineation
Group Name: Small Cyprinids

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs and larvae) in appropriate habitat.
Separation Barriers: Dam lacking a suitable fishway; high waterfall; upland habitat. For some species (e.g., slender chub), an impoundment may constitute a barrier. For others (e.g., flame chub) a stream larger than 4th order may be a barrier.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Data on dispersal and other movements generally are not available. In some species, individuals may migrate variable distances between spawning areas and nonspawning habitats.

Separation distances (in aquatic kilometers) for cyprinids are arbitrary but reflect the presumption that movements and appropriate separation distances generally should increase with fish size. Hence small, medium, and large cyprinids, respectively, have increasingly large separation distances. Separation distance reflects the likely low probability that two occupied locations separated by less than several kilometers of aquatic habitat would represent truly independent populations over the long term.

Because of the difficulty in defining suitable versus unsuitable habitat, especially with respect to dispersal, and to simplify the delineation of occurrences, a single separation distance is used regardless of habitat quality.

Occupied locations that are separated by a gap of 10 km or more of any aquatic habitat that is not known to be occupied represent different occurrences. However, it is important to evaluate seasonal changes in habitat to ensure that an occupied habitat occurrence for a particular population does not artificially separate spawning areas and nonspawning areas as different occurrences simply because there have been no collections/observations in an intervening area that may exceed the separation distance.

Date: 21Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 08Dec1995
NatureServe Conservation Status Factors Author: Hammerson, G., and S. Vives
Management Information Edition Date: 20May1991
Management Information Edition Author: S. P. VIVES, BIOLOGY, LANDRUM #8042, GSU, STATESBORO, GA 30458
Element Ecology & Life History Edition Date: 08Dec1995
Element Ecology & Life History Author(s): Hammerson, G.

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